Electrical load management system and method

ABSTRACT

Techniques for distributing electrical power to a plurality of electrical loads can include coupling an existing group of electrical loads to a common power source through a load management system, measuring an aggregate group current drawn by at least the existing group of electrical loads and comparing the measured aggregate group current to an aggregate group current threshold value. When the measured aggregate group current exceeds the aggregate group current threshold value, increase a number of subgroups of the existing group, using subgroups that are formed without requiring information about individual current associated with the individual electrical loads, sequentially apply power to individual subgroups during non-overlapping time periods, sequentially measure at least a corresponding current drawn by the individual subgroups while power is applied to the subgroups, and sequentially comparing the measured current to a threshold value.

CLAIM OF PRIORITY AND CROSS-REFERENCES

This application is a continuation of U.S. patent application Ser. No.17/846,787, titled “ELECTRICAL LOAD MANAGEMENT SYSTEM AND METHOD,” toWilliam Tischer and filed on Jun. 22, 2022, which is a continuation ofU.S. patent application Ser. No. 17/221,548, titled “ELECTRICAL LOADMANAGEMENT SYSTEM AND METHOD,” to William Tischer and filed on Apr. 2,2021, which is a continuation of U.S. patent application Ser. No.16/508,889, titled “ELECTRICAL LOAD MANAGEMENT SYSTEM AND METHOD,” toWilliam Tischer and filed on Jul. 11, 2019, which is a continuation ofU.S. patent application Ser. No. 15/512,431, titled “ELECTRICAL LOADMANAGEMENT SYSTEM AND METHOD,” to William Tischer and filed on Mar. 17,2017, which is a U.S. National Stage Filing under 35 U.S.C. § 371 ofInternational Patent Application Serial No. PCT/US2015/050930, titled“ELECTRICAL LOAD MANAGEMENT SYSTEM AND METHOD,” to William D. Tischerand filed on Sep. 18, 2015, and published on Mar. 24, 2016 asWO2016/044719 A1, which claims the benefit of priority of U.S.Provisional Patent Application No. 62/052,244, titled “ELECTRICAL LOADMANAGEMENT SYSTEM AND METHOD,” to William D. Tischer and filed on Sep.18, 2014, which are incorporated by reference herein in their entirety.

This application is related to U.S. patent application Ser. No.13/174,637 titled “ELECTRICAL LOAD MANAGEMENT SYSTEM AND METHOD,” byWilliam Tischer and filed on Jun. 30, 2011, and U.S. patent applicationSer. No. 14/480,185 titled “ELECTRICAL LOAD MANAGEMENT SYSTEM ANDMETHOD,” by William Tischer and filed on Sep. 8, 2014, the contents ofeach are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the invention generally relate the management ofelectrical loads and more particularly relate to load management ofelectrical devices requesting more power than is available from a commonpower source.

BACKGROUND

There are many instances in which multiple electrical loads areconnected to and powered by a single, common electrical power source.The common power source may be designed to provide sufficient power forall of the electrical loads, to ensure that each load is adequatelypowered.

In certain circumstances, though, it may be desirable to provide powerto a number of electrical loads from a power source that does not supplyenough power to adequately power all of the electrical loads. Requestingmore than the available power may in some cases lead to inadequatedevice performance as well as, or in addition to, activation ofprotection circuitry built into the power source. For example, anoverload can result due to a circuit breaker tripping, an over-currentor current limiting circuit causing a power source voltage fold-back, orother method of limiting the distributed power to a known acceptablelevel without exceeding the source power available. Activation of theprotection features can lead to reduced or no power reaching theelectrical load(s) that needs powering. Consequently, the functionalityof the load(s) attached to the power source can be reduced or disabled.

Source power might be limited for a number of reasons, including, forexample, the size of wiring, circuit breaker limits, National andInternational Electrical Codes, development of harmonic currents,vehicle electrical power limits, or limits stemming from currentlyavailable alternative energy sources such as solar or wind-generatedpower.

One example of an arrangement that may be subject to these types oflimitations is a computer notebook or laptop charging cart or chargingstation. There are many situations in which multiple laptop computersare simultaneously used. For example, multiple laptop computers arewidely used in classrooms for educational purposes. In many cases, 10-40notebooks are simultaneously used in the classroom. Typical laptop cartsare cabinets with shelves for the laptops to rest on and power and/orcommunication connections for charging and/or using the laptops.

In many cases the power consumption required to simultaneously chargeand/or use many notebooks can exceed the limits set forth by theNational Electrical Code and foreign equivalents for alternating current(AC) line voltages. This type of power consumption may also often exceedthe capacity of a direct current (DC) power source that provides thebulk charge current for the electronics that charge notebook batteriesdirectly. Known charging methods require a user to manually switch powerbetween groups of notebooks or batteries to keep the peak current drawwithin the limitations of the physical configuration. If computer cartsor charging stations are provided with auxiliary power take-offs, knownmethods also require the user to manually switch on any external devicesto be powered while internal devices are switched off.

SUMMARY

According to an aspect of the invention an electrical load managementsystem is provided for switching electrical power among a number ofelectrical loads. The load management system can include an electricalpower input that couples the load management system with a common powersource and a plurality of electrical power outputs that couple withmultiple electrical loads. A number of switches couple the power inputto the power outputs. A current sensor is coupled to the power outputsand senses a current drawn by one or more of the power outputs. Acontroller is coupled to the switches and the current sensor, and isconfigured to measure a current drawn by each of the power outputs andrespective electrical loads. The controller also groups the poweroutputs and electrical loads into one or more load groups based on aswitched current limit determined for the system and the measuredcurrents of the electrical loads. The load groups are defined so thatthe sum of electrical load currents in each load group does not exceedthe switched current limit. The controller is also configured toactivate the switches to apply electrical power from the common powersource to the load groups according to a power sequence.

Another aspect of the invention provides a method for distributingelectrical power to electrical loads. The method includes measuring acurrent drawn by each of a number of electrical loads coupled to acommon power source through a load management system. The electricalloads are grouped into one or more load groups based on a switchedcurrent limit and the measured currents of the electrical loads. Thegrouping is configured so that, for each load group, a sum of themeasured currents of the electrical loads in the load group does notexceed the switched current limit. The method also includes applyingelectrical power from the common power source to the load groups byswitching the electrical power to each of the load groups according to apower sequence.

Another aspect of the invention provides for managing the electricalload of a charging station. The charging station includes an electricalpower input configured to couple the charging station with a commonpower source and multiple switched electrical power outputs configuredto couple the charging station with a number of electrical loads forcharging. The charging station also includes a number of switchescoupled between the power input and the switched power outputs forapplying electrical power from the common power source to the switchedpower outputs. A current sensor is coupled to the switched power outputsfor sensing a current drawn by one or more of the switched poweroutputs. In one embodiment, an optional un-switched power output iscoupled to the electrical power input and configured to couple thecharging station with an un-switched electrical load, while a secondcurrent sensor coupled to the un-switched output senses a current drawnby the un-switched power output. In both embodiments, the chargingsystem includes a controller coupled to the switches, the first currentsensor, and optionally the second current sensor. The controllermeasures with the first current sensor a current drawn by each of theelectrical loads respectively coupled to the switched power outputs.After measuring the currents, the controller groups the switched poweroutputs and respective electrical loads into one or more load groupsbased on a switched current limit and the measured currents of theelectrical loads such that, for each load group, a sum of the measuredcurrents of the electrical loads in the load group does not exceed theswitched current limit. The controller is also configured to activatethe switches to apply electrical power from the common power source tothe load groups according to a power sequence. In some cases thecontroller is configured to determine a switched current limit based onthe current drawn by the optional un-switched power output and/or acurrent limit of the common power source.

These and various other features and advantages will be apparent from areading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIG. 1 is a high-level diagram illustrating multiple functions of a loadmanagement system in accordance with an embodiment of the invention.

FIG. 2 is a high-level schematic of a load management system inaccordance with an embodiment of the invention.

FIG. 3 is a flow diagram illustrating a method for applying power to anumber of un-switched and switched electrical devices in accordance withan embodiment of the invention.

FIG. 4 is an illustration of an indicator panel for a load managementsystem in accordance with an embodiment of the invention.

FIG. 5A is a perspective view of a charging station in accordance withan embodiment of the invention.

FIG. 5B is a perspective view of a charging station in accordance withan embodiment of the invention.

FIG. 5C is another perspective view of the charging station of FIG. 5B.

FIG. 5D is a rear perspective view of the charging station of FIG. 5B.

FIG. 6A is a top plan view of a cart in accordance with an embodiment ofthe invention.

FIG. 6B is a front perspective view of the cart of FIG. 6A.

FIG. 6C is a front plan view of the cart of FIG. 6A.

FIG. 6D is a side plan view of the cart of FIG. 6A.

FIG. 7A is a front perspective view of a cart with its doors opened inaccordance with an embodiment of the invention.

FIG. 7B is a rear perspective view of the cart of FIG. 7A with its rearpanel removed.

FIG. 7C is a front perspective view of an auxiliary power outlet havinga cover in the open position in accordance with an embodiment of theinvention.

FIG. 7D is a front perspective view of an auxiliary power outlet havinga cover in the open position in accordance with an embodiment of theinvention.

FIG. 8 is a high-level schematic of a power supply system for a notebookcharging cart in accordance with an embodiment of the invention.

FIGS. 9A-9C are a flow diagram illustrating a method of chargingmultiple notebook computers in accordance with an embodiment of theinvention.

FIGS. 10A-10B are a flow diagram illustrating a method of chargingmultiple notebook computers in accordance with an embodiment of theinvention.

FIGS. 11A-11C are a flow diagram illustrating a method of chargingmultiple notebook computers in accordance with an embodiment of theinvention.

FIGS. 12A-12B are a flow diagram illustrating a method of chargingmultiple notebook computers in accordance with an embodiment of theinvention.

FIGS. 13A-13C are a flow diagram illustrating another method of chargingmultiple notebook computers in accordance with an embodiment of theinvention.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of ordinary skill inthe field of the invention. Those skilled in the art will recognize thatmany of the noted examples have a variety of suitable alternatives.

FIG. 1 is a high-level diagram illustrating a load management system 100according to an embodiment of the invention. In general, the system 100can provide an interface between a power source 102 and multipleelectrical loads 104, such as for controlling distribution of electricalpower from the power source 102 to one or more of the electrical loads104. The load management system 100 can provide a useful solution formanaging electrical loads in a variety of contexts. For example, thesystem 100 can be used for powering and/or charging large numbers oflaptop computers (also referred to herein as “notebook computers” or“notebooks”) such as can be used in a school classroom or in a businesssetting. The system 100 can additionally or alternatively be used tomanage electrical power for a group of mobile computing devices, such asincluding for example, a tablet computer, a cell phone, a smart phone, apersonal digital assistant, a camera, a music player, and/or a globalpositioning satellite (GPS) device. In some instances the system 100 maybe useful for providing electrical power to a number of electrical loadscoupled to a vehicle (e.g., automobile, aircraft, etc.) power system. Ofcourse, these are just a few contemplated examples for using the system100, and the system 100 may also be useful in other situations.

In some cases the load management system 100 could be useful formanaging delivery of electrical power from an alternative energy sourcesuch as wind or solar power to multiple electrical loads. Other energysources may be coupled to the system 100, and the particular format orconfiguration of the electrical power may vary depending upon therequirements of a particular embodiment. As will be discussed furtherherein, in some cases the power source 102 may provide AC power or DCpower. In some embodiments the electrical power is pulsed, sinusoidal,non-sinusoidal, or has another waveform.

As shown in FIG. 1 , the load management system 100 can provide a numberof functions that may be useful for distributing power to the multipleelectrical loads 104. In particular examples, the system 100 can providepower source protection circuitry 110, inrush current limiting circuitry112, control logic circuitry 114, current sensing circuitry 116,switched power distribution circuitry 118, and non-switched powerdistribution circuitry 120. According to some embodiments, thefunctionality of the load management system 100 can be implemented andprovided by hardware and firmware or software, or a combination ofhardware, firmware, and software. The illustrated system 100 is just oneexample of a load management system described herein, and otherembodiments may provide all or only some of the circuits or functionsshown in FIG. 1 , or may provide different circuits or functions notdepicted. Several of the functions for the illustrated load managementsystem 100 will be described in more detail hereinafter.

FIG. 2 is a high-level schematic of a load management system 200 inaccordance with an embodiment of the invention. The system 200 generallyprovides an interface between an electrical power input 202 and multipleelectrical power outputs 204. The power outputs 204 are coupled to theinput through switches 206, which serve to selectively transmitelectrical power to the power outputs 204. Control of the switches 206and thus distribution of power from the power input 202 to one or moreof the power outputs 204 is controlled and managed by a controllercircuit 208. A current sensor 210 is coupled to the electrical poweroutputs 204 and the controller 208, thus allowing the controller 208 tomake decisions about power distribution based on measured currents drawnby one or more of the power outputs 204. In this embodiment the loadmanagement system 200 also includes two un-switched power outputs,including an un-switched auxiliary power output 212 and an un-switchednetworking power output 214. The networking power output 214 is coupledto the first current sensor 210, which also provides measurements ofcurrent drawn by the networking power output 214. A second currentsensor 216 is coupled to the un-switched auxiliary output 212 andprovides measurements of current drawn by the auxiliary output 212.

Referring again to FIG. 2 , the electrical power input 202 is configuredto couple the load management system with a single, common power source(not shown). In this embodiment, the power input 202 is a power outletand site power is brought into the system 200 through a power cord andconnected plug. Other types of electrical power inputs may also be used,including other removable connectors, as well as hard-wired connections.In some embodiments, the electrical power is then distributed to thesystem 200 through a protection and conditioning circuit 220. Theprotection and conditioning circuit 220 includes circuit breakers and/orresettable fuses (e.g., PTC devices) and a line filter to controlemissions from the rest of the load management system 200 and electricalloads attached to the power outputs 204. The load management system 200is configured in this example to receive AC power at the power input202. Other embodiments may be configured to receive DC power.

The load management system 200 receives the electrical power through thepower input 202, and then routes it to one or more of the power outputs204 through switches 206. The power outputs 204 are configured to couplethe load management system with one or more electrical loads (not shownin FIG. 2 ). In the example shown in FIG. 2 , the power outputs 204 areconfigured as power outlets that can receive a plug connected to anelectrical load. Other types of connections may be used depending uponthe situation, including outputs hard-wired to the electrical loads.

The switches 206 are coupled between the power input 202 and the poweroutputs 204. Accordingly, the power outputs 204 are also referenced as“switched” power outputs. The switches 206 can be implemented using anysuitable switching device known in the art. Examples include, but arenot limited to, solid-state relays (AC and DC), triacs (AC), and MOSFETS(DC). The switches 206 are coupled to the controller 208, which operatesthe switches through, e.g., low-level control logic signals.

The controller 208 receives operating power from the power input 202 viaan input 222. In the case that the electrical power is AC, thecontroller 208 may also include an AC/DC converter for generating a DCsignal to power the controller 208. The controller 208 includes aprocessing component 224 configured to provide the desired control forthe system 200. The processing component can be implemented in anysuitable combination of hardware, firmware, and/or software. In somecases the processing component includes a microcontroller and associatedfirmware stored in integrated memory. In one example the processingcomponent 224 is implemented with a programmable integrated circuit(PIC) or a programmable logic device (PLD), though other types ofprogrammable processors are also contemplated.

As shown in FIG. 2 , the controller 208 is coupled to the current sensor210, which is in turn coupled to each of the power outputs 204 throughthe switches 206. The current sensor 210 can be implemented using anysuitable approach, including, for example, a resistive shunt, aHall-effect sensor, or an inductive sensor, among others. Through thesensor 210, the controller 208 can monitor and measure the current drawnby one or more power outputs 204 (e.g., by the electrical load coupledto the output) alone or in various combinations. To measure a currentdrawn by a particular power output 204, the controller 208 is configuredto activate the switch 206 corresponding to the particular power output204 while deactivating the switches for the other power outputs. Thecontroller 208 then uses the current sensor 210 to monitor the currentdrawn from the power input 202.

In the example shown in FIG. 2 , a single current sensor 210 is used tomeasure current drawn by each of the electrical power outlets 204. It isalso contemplated that multiple current sensors could be used to morequickly (e.g., simultaneously) measure currents drawn by multipleelectrical power outputs. For example, a current sensor could bepositioned along each of the circuit branches leading to a particularpower output 204.

According to some embodiments, the controller 208 is configured todistribute the available electrical power from the power input 202 tothe power outputs 204 by grouping the power outputs 204 (and respectiveloads) and then selectively applying the electrical power to the groupsof power outputs according to a power sequence. It has been determinedthat this can be a useful methodology for powering electrical loadsconnected to the power outputs 204, especially in cases in which thecombined current drawn by the power outputs 204 and respectiveelectrical loads (not shown) may be greater than the current provided bythe electrical power input 202. According to this approach, thecontroller 208 is configured to measure the current drawn by each of theswitched power outputs 204 and then group the power outputs 204 andrespective electrical loads into one or more load groups based on themeasured currents and a determined switched current limit. In oneembodiment the switched power outputs 204 are grouped such that a sum ofthe measured currents of the power outputs 204 in a particular groupdoes not exceed the switched current limit. The controller 208 can thenactivate the appropriate switches 206 in order to apply the electricalpower to the defined groups in sequence.

The switched current limit is a determined threshold that represents adesired limit for the amount of electrical power being applied to thepower outputs 204 from the power input 202 at any one time. The switchedcurrent limit can be determined using a number of factors, including,for example, the current capacity of the electrical power input 202. Asdiscussed below, in some circumstances the switched current limit canalso or alternatively be determined based on an amount of electricalpower distributed to outputs other than the switched outputs 204.

According to some embodiments, a load management system can also provideun-switched (e.g., continuous) electrical power to one or more poweroutputs. As shown in FIG. 2 , the load management system 200 includestwo un-switched power outputs, namely an un-switched auxiliary poweroutput 212 and an un-switched networking power output 214. Thenetworking power output 214 is coupled to the first current sensor 210,which can provide a measurement of the current drawn by the networkingpower output 214. A second current sensor 216 is coupled to theun-switched auxiliary output 212 and provides measurements of currentdrawn by the auxiliary output 212.

Any desirable number of un-switched power outputs can be included in theload management system 200. A current sensor coupled to an un-switchedoutput can be useful to measure the current drawn by the un-switchedoutput. For example, the current sensor 216 in the load managementsystem 200 allows the controller 208 to readily determine the auxiliaryport current, which may vary or periodically shut off depending upon thetype of load connected to the port 212. In addition, the first currentsensor 210 allows the controller 208 to easily determine the currentdrawn by the networking power output 214 when the switches 206 have beendeactivated.

Powering electrical loads through the un-switched power outputs allowsthe load management system 200 to prioritize electrical powerdistribution for those loads over the loads connected to the switchedpower outputs 204. For example, the un-switched power outputs 212, 214are not subject to the switched power sequence used with the switchedoutputs 204, and thus the un-switched outputs and connected electricalloads can receive continuous power while the switched outputs 204 mayonly receive intermittent power in some cases. In addition, in somecases a portion of the available electrical power from the electricalpower input 202 is effectively dedicated to the un-switched poweroutputs, thus decreasing the amount of electrical power available fordistribution to the switched power outputs 204. Accordingly, in somecases the switched current limit for the switched outputs 204 isdetermined based upon the current(s) drawn by the un-switched load(s).

As an example, in one embodiment the controller 208 is configured tosense through the current sensor 216 if an external un-switched loadconnected to the auxiliary port 212 is powered on. The controller 208measures the current drawn by the auxiliary port 212 and then subtractsthis measured current from the current previously available to theswitched power outputs 204. The switched current limit for the switchedpower outputs can thus be determined or adjusted based on the amount ofelectrical power being reserved for the un-switched power outputs andloads. In some cases this approach can maximize the current available tothe un-switched outputs 212, 214, while still providing a reduced powerlevel to the switched power outputs 204. Once the un-switched load ordevice is turned off or unplugged from the un-switched output,controller 208 can automatically increase the switched current limit forthe switched outputs.

In accordance with this disclosure, rather than measuring the currentdrawn by each power output 204 and then determining the number of poweroutputs that can be on without exceeding a threshold, as describedabove, the controller 208 can switch on all power outputs 204, applypower to all loads through the power outputs 204 at the same time, andthen detect the total current through the current sensor, e.g., currentsensor 210. If the total current is above the threshold value, thecontroller 208 can remove the power to the power outputs 204, divide thepower outputs 204 into groups, and reapply power. If the current drawnby a group of the power outputs 204 exceeds the threshold, thecontroller 208 can remove the power to the group of power outputs 204,divide the grouped power outputs 204 into smaller groups, and reapplypower. The controller 208 can continue this process until the current isbelow the threshold.

By way of a non-limiting specific example and as seen in the flowdiagram of FIGS. 13A-13C, in some examples, the load management system100 (FIG. 1 ) can couple an existing group of electrical loads 104 (FIG.1 ) to a common power source 102 (FIG. 1 ) through the load managementsystem and at 1301 the controller 208 can determine whether the inputvoltage of the power source 102 is 120 volts or 240 volts. Although FIG.2 depicts a system with 6 banks 204, the following specific exampledescribes a system with 8 banks 204. The techniques described, however,are applicable to systems with more than 8 banks or fewer than 8 banks.Continuing with the example, based on the input voltage, the controller208 can retrieve one or more stored threshold current values frommemory, e.g., a first threshold at 1302 and a second threshold at 1303.

At 1304, the controller 208 can then determine whether the power onswitch is ON or in standby. If at 1304 the power on switch is in“standby” (“YES” branch of 1304), then the relays 206 to all banks 204are OFF at 1305. In some examples, the controller 208 can at 1305 alsoturn OFF the auxiliary power output 212 and the switch/WAP power output214. If the power on switch is ON (“NO” branch of 1304), then, in someexamples, the controller 208 can determine whether an N-number deviceswitch, e.g., 30 device switch, is ON at 1306. If the N-number deviceswitch is ON (“YES” branch of 1306), then the controller 208 can adjustvarious charging parameters, e.g., thresholds, timers, and the like,which are beyond the scope of this disclosure.

If the N-number device switch is not ON (“NO” branch of 1306) then at1307 the controller 208 can turn ON the relays 206 to all banks 204,e.g., banks 1-8, where all the electrical loads 104 coupled to all 8banks 204 form an existing group of electrical loads. The controller 208can switch ON each bank 204, e.g., for 1 second, and at 1308 apply powerto the auxiliary power output 212, and the switch/WAP power output 214.At 1309 the controller 208 can determine the amount of current throughthe current sensor 210 and the controller 208 can compare the determinedcurrent through the current sensor 210 to a first threshold value, e.g.,12 amps. That is, the controller 208 can measure an aggregate groupcurrent drawn by at least the existing group of electrical loads 104coupled to banks 204 and compare the measured aggregate group current toan aggregate group current threshold value. The controller 208 does notrequire information about individual current associated with theindividual electrical loads; rather the controller 208 can use theaggregate current of the group of electrical loads. If the determinedcurrent exceeds the first threshold (“YES” branch of 1309), thecontroller 208 can turn off the power and provide an alert, e.g., LEDindication, at 1310.

If the determined current does not exceed the first threshold (“NO”branch of 1309), the controller 208 can switch on all the relays at 1311and apply power to all banks, e.g., banks 1-8, and apply power to theauxiliary power output 212, and the switch/WAP power output 214. At1312, the controller 208 can again determine the current through thecurrent sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current is less than thesecond threshold (“YES” branch of 1312), then the controller 208 candetermine that there are no power issues and can leave the banks, e.g.,banks 1-8, switched on (at 1311).

However, if the determined current is greater than the second threshold,e.g., 10 amps, (“NO” branch of 1312) then the controller 208 switchesoff the power to all the banks, e.g., banks 1-8, and divides theelectrical loads connected to the banks into groups. That is, when themeasured aggregate group current exceeds the aggregate group currentthreshold value, the controller 208 can increase a number of subgroupsof the existing group, using subgroups that are formed without requiringinformation about individual current associated with the individualelectrical loads. For example, the controller 208 can divide theexisting group of electrical loads of the 8 banks into two subgroupshaving four banks each, e.g., divide the existing subgroup into twosubgroups, and distribute the plurality of electrical loads across theincreased number of subgroups.

Then, the controller 208 can sequentially apply power to individualsubgroups during non-overlapping time periods. The controller 208 cansequentially measure at least a corresponding current drawn by theindividual subgroups while power is applied to the subgroups. Thecontroller 208 can sequentially comparing the measured current to athreshold value, and when the measured current exceeds the thresholdvalue, repeat increasing the number of subgroups, sequentially applyingpower, sequentially measuring at least the corresponding current, andsequentially comparing at least the measured current to a thresholdvalue. If the measured current does not exceed the threshold value, thecontroller 208 can repeat sequentially applying power, sequentiallymeasuring at least the corresponding current, and sequentially comparingthe measured current to a threshold value.

Repeating the process includes repeating until a subgroup criterion ismet, which can include 1) the measured current corresponding to each ofsubgroups being below the corresponding threshold value associated withthe subgroup or 2) the subgroups have been increased to a maximumavailable number of subgroups and the aggregate group current exceedsthe aggregate group current threshold value. Sequentially measuring atleast a corresponding current drawn by the individual subgroups whilepower is applied to the subgroups, can include including in the measuredcurrent, in addition to the current drawn by the individual subgroup, atleast one of (1) an auxiliary power output current and (2) a switchedpower output current. Increasing the number of subgroups furtherincludes correspondingly decreasing the non-overlapping time periodassociated with subgroups for the sequentially applying power to theindividual subgroups.

More specifically, at 1313, the controller 208 can switch on the firstsubgroup of electrical loads, e.g., banks 1-4, and apply power. At 1314,the controller 208 can determine the current for banks 1-4 through thecurrent sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current for banks 1-4 isless than the second threshold (“YES” branch of 1314), then at 1315 thecontroller 208 can initiate a first timer, e.g., an 8 minute timer, andcharge the loads connected to banks 1-4 for the duration of the firsttimer. Once the first timer has expired (“YES” branch of 1315), thecontroller 208 can then switch on the second subgroup of electricalloads, e.g., banks 5-8 and apply power at 1316. At 1317, the controller208 can determine the current for banks 5-8 through the current sensor210 and compare the determined current to a second threshold, e.g., 10amps. If the determined current is less than the second threshold (“YES”branch of 1317), then the controller 208 can initiate a first timer at1318, e.g., an 8 minute timer, and charge the loads connected to banks5-8 for the duration of the first timer. Once the first timer hasexpired (“YES” branch of 1318), the loads are charged sufficiently thatthey do not need to be grouped any longer and stay within the limits ofthe current available, and the method returns to 1301.

If the determined current for the first subgroup of electrical loads(“NO” branch of 1314), e.g., banks 1-4, is greater than the secondthreshold, e.g., 10 amps, or if the determined current for the secondgroup of banks (“NO” branch of 1317), the controller 208 can switch offpower and divide the electrical loads by increasing the number ofsubgroups, e.g., increasing the number of subgroups by one. For example,the controller can divide the group of electrical loads connected tobanks 1-8 into three subgroups: a first subgroup having banks 1-3, asecond subgroup having banks 4-6, and a third subgroup having banks 7-8.At 1319, the controller 208 can switch on the first subgroup of banks,e.g., banks 1-3, and apply power. At 1320, the controller 208 candetermine the current for banks 1-3 through the current sensor 210 andcompare the determined current to the second threshold, e.g., 10 amps.If the determined current for banks 1-3 is less than the secondthreshold (“YES” branch of 1320), then the controller 208 can initiate asecond timer at 1321, e.g., a 5 minute timer, and charge the loadsconnected to banks 1-3 for the duration of the second timer. In thismanner, the power to the subgroups is applied sequentially duringnon-overlapping time periods.

At 1322, the controller 208 can then switch on the second subgroup ofelectrical loads, e.g., banks 4-6 and apply power upon expiration of thesecond timer. At 1323, the controller 208 can determine the current forbanks 4-6 through the current sensor 210 and compare the determinedcurrent to a second threshold, e.g., 10 amps. If the determined currentis less than the second threshold (“YES” branch of 1323), then thecontroller 208 can initiate a second timer at 1324, e.g., a 5 minutetimer, and charge the loads connected to banks 4-6 for the duration ofthe second timer. Finally, at 1325 the controller 208 can then switch onthe third subgroup of electrical loads, e.g., banks 7-8 and apply power.At 1326, the controller 208 can determine the current for banks 7-8through the current sensor 210 and compare the determined current to asecond threshold, e.g., 10 amps. If the determined current is less thanthe second threshold (“YES” branch of 1326), then the controller 208 caninitiate the second timer at 1327, e.g., a 5 minute timer, and chargethe loads connected to banks 7-8 for the duration of the second timer.Once the second timer has expired (“YES” branch of 1327), the loads arecharged sufficiently that they do not need to be grouped any longer andstay within the limits of the current available, and the method returnsto 1301.

If the determined current for the first subgroup of electrical loads,e.g., banks 1-3, the second group of banks, e.g., banks 4-6, or thethird group of banks, e.g., banks 7-8, is greater than the secondthreshold, e.g., 10 amps, (“NO” branches of 1320, 1323, 1326) thecontroller 208 can switch off power and divide the electrical loadsfurther by increasing the number of subgroups. For example, thecontroller can divide the group of electrical loads connected to banks1-8 into four subgroups of electrical loads having two banks each: afirst subgroup having banks 1-2, a second subgroup having banks 3-4, athird subgroup having banks 5-6, and fourth subgroup having banks 7-8.The controller 208 can switch on the first subgroup of electrical loads,e.g., banks 1-2, and apply power at 1328. At 1329, the controller 208can determine the current for banks 1-2 through the current sensor 210and compare the determined current to the second threshold, e.g., 10amps. If the determined current for banks 1-2 is less than the secondthreshold (“YES” branch of 1329), then the controller 208 can initiate athird timer at 1330, e.g., a 4 minute timer, and charge the loadsconnected to banks 1-2 for the duration of the second timer.

At 1331, the controller 208 can then switch on the second subgroup ofelectrical loads, e.g., banks 3-4 and apply power. At 1332, thecontroller 208 can determine the current for banks 3-4 through thecurrent sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current is less than thesecond threshold (“YES” branch of 1332), then the controller 208 caninitiate the third timer at 1333, e.g., a 4 minute timer, and charge theloads connected to banks 3-4 for the duration of the third timer.

At 1334, the controller 208 can then switch on the third subgroup ofelectrical loads, e.g., banks 5-6 and apply power. At 1335, thecontroller 208 can determine the current for banks 5-6 through thecurrent sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current is less than thesecond threshold (“YES” branch of 1335), then the controller 208 caninitiate the third timer 1336, e.g., a 4 minute timer, and charge theloads connected to banks 5-6 for the duration of the third timer.

Finally, at 1337 the controller 208 can switch on the fourth subgroup ofelectrical loads, e.g., banks 7-8 and apply power. At 1338, thecontroller 208 can determine the current for banks 7-8 through thecurrent sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current is less than thesecond threshold (“YES” branch of 1338), then the controller 208 caninitiate the third timer at 1339, e.g., a 4 minute timer, and charge theloads connected to banks 7-8 for the duration of the third timer. Oncethe third timer has expired (“YES” branch of 1339), the loads arecharged sufficiently that they do not need to be grouped any longer andstay within the limits of the current available, and the method returnsto 1301.

If the determined current for the first subgroup of electrical loads,e.g., banks 1-2, the second subgroup of electrical loads, e.g., banks3-4, the third subgroup of electrical loads, e.g., banks 5-6, or thefourth subgroup of electrical loads, e.g., banks 7-8, is greater thanthe second threshold, e.g., 10 amps, (“NO” branches of 1329, 1332, 1335,1338) the controller 208 can switch off power and further divide theelectrical loads by increasing the number of subgroups. That is, thecontroller 208 can increase the number of subgroups to 8 such that firstsubgroup of electrical loads is connected to bank 1, the second subgroupof electrical loads is connected is connected to bank 2, the thirdsubgroup of electrical loads is connected to bank 3, the fourth subgroupof electrical loads is connected to bank 4, and so forth until theeighth subgroup of electrical loads is connected to bank 8. At 1340, thecontroller 208 can switch on bank 1 and apply power. At 1341, thecontroller 208 can determine the current for bank 1 through the currentsensor 210 and compare the determined current to the second threshold,e.g., 10 amps. If the determined current for bank 1 is less than thesecond threshold (“YES” branch of 1341), then the controller 208 caninitiate a fourth timer, e.g., a 2 minute timer at 1342, and charge theloads connected to bank 1 for the duration of the fourth timer.

At 1343, the controller 208 can then switch on bank 2 and apply power.At 1344, the controller 208 can determine the current for bank 2 throughthe current sensor 210 and compare the determined current to a secondthreshold, e.g., 10 amps. If the determined current is less than thesecond threshold (“YES” branch of 1344), then the controller 208 caninitiate the fourth timer at 1345, e.g., a 2 minute timer, and chargethe loads connected to bank 2 for the duration of the fourth timer. Thecontroller 208 can then repeat this process for the remaining banks,e.g., banks 3-8, as seen at 1346-1363. Once the fourth timer has expired(“YES” branch of 1363), the loads are charged sufficiently that they donot need to be grouped any longer and stay within the limits of thecurrent available, and the method returns to 1301. If, however, thedetermined current for any of banks 1-8 is greater than the threshold(“NO” branches of 1341, 1344, 1347, 1350, 1353, 1356, 1359, 1362), thanat 1364 the controller 208 can turn the power off to all the banks 1-8and at 1365 the controller 208 can turn the LEDs OFF, for example,indicating that no banks were able to charge.

In this manner, the controller 208 can measure current continuously andgroup the electrical loads, if needed. This technique can improve thecharging efficiency of the system by eliminating the measurement time ofindividual load groups, which are fixed times based on the time it takesbatteries to reach peak current. That is, a pre-determined measurementtime is often used in order for batteries to reach peak current for themeasurement to be accurate. In the techniques described with respect toFIGS. 13A-13C, this measurement time is incorporated into the continuousaggregate current measurement. For example, some battery systems cantake up to two minutes to reach peak current compared to theapproximately 30-seconds for other battery systems. If the measurementtime is two minutes, the iterative measurement and grouping process canadd a long time to complete the charge cycle. Using the techniquesdescribed above with respect to FIGS. 13A-13C, this measurement time canbe eliminated, thereby improving the overall charge time.

A load management system, such as the system 200 illustrated in FIG. 2 ,can be modified to be compatible with a wide variety of applications,and may be incorporated into a number of larger systems. As will bediscussed with reference to FIGS. 5-12 , some embodiments of theinvention provide a load management system configured for charging anumber of laptop computer batteries, while also providing electricalpower for external or peripheral devices. For example, the loadmanagement system may provide electrical power to multiple notebooks ornotebook batteries through multiple switched power ports, while alsoproviding electrical power for an accessory such as a printer,projector, scanner, or other device, through an un-switched power port.Accordingly, the load management system 200 can be helpful for chargingnotebook batteries, while still allowing use of the peripheral devicesand accessories that are all powered using a single power sourceinsufficient to fully power all connected devices simultaneously.

In some cases the load management system may be incorporated within abattery charging station, such as a desktop charging station (e.g., asin FIGS. 5A-5D) or a notebook charging cart (e.g., as shown in FIGS. 6and 7 ). Embodiments of the invention are not limited to notebookapplications, however, and may be directed to providing power for a widevariety of electrical devices (i.e., electrical loads). For example, theelectrical loads 204 can include devices such as a tablet computer, acell phone, a smart phone, a personal digital assistant, a camera, amusic player, and/or a global positioning satellite (GPS) device, amongothers.

FIG. 3 is a flow diagram illustrating a method 300 for applying power toa number of un-switched and switched electrical devices in accordancewith an embodiment of the invention. According to one embodiment, themethod 300 can be implemented with a controller configured to performthe steps in the method, such as the controller 208 described withrespect to the load management system 200 in FIG. 2 . According to oneaspect, the illustrated method 300 generally enables a powerdistribution scheme in which a limited amount of available input poweris distributed among a number of intermittent, switched loads, and ifapplicable, one or more continuous, un-switched loads. In some cases themethod 300 also allows for prioritizing distribution of the input power.For example, in some cases priority is given to certain un-switchedloads to provide full operation on-demand. In some cases power remainingafter providing for the un-switched loads is applied to lower priorityloads and may be switched between a between groups of lower priorityloads to maximize the capability of the remaining input power.

Returning to FIG. 3 , in this example the method 300 generally includesmeasuring and/or determining the current drawn by certain loads,grouping a number of switched loads based on the currentmeasurements/determinations, and then applying power to the groups ofswitched loads one at a time. While a number of steps are illustrated inan order in FIG. 3 , it should be appreciated that the steps in themethod need not necessarily be performed in the illustrated order. Inaddition, while the method 300 is discussed in terms of applying powerto “devices”, it should be understood that the method is consideredapplicable to electrical loads in general.

In cases in which power is to be applied to un-switched or continuouslypowered loads, a first step in the illustrated method 300 can includeproviding power to any un-switched devices and measuring the currentdrawn by those devices (302). Referring to FIG. 2 , this step couldinclude, for example, applying electrical power to the auxiliary poweroutput 212 and then measuring the current drawn by the auxiliary output212 using the current sensor 216 coupled to the controller 208. Inaddition, this step could include deactivating the switches 206 andapplying electrical power to the networking power output 214 and thenmeasuring the current drawn by the output 214 with the first currentsensor 210 coupled to the controller 208. After measuring or otherwisedetermining the currents (302), the current values may be stored inmemory for future use.

Returning to FIG. 3 , the method 300 further includes determining aswitched current limit (304) for use in grouping electricalloads/devices. As referenced above, a switched current limit is adetermined threshold that represents a limit for the amount ofelectrical power that is available for switched loads at any one time.The switched current limit can be determined using a number of factors,including, for example, the current capacity or a current limit of theelectrical power input as well as currents drawn by un-switched loadsand measured in step 302. According to one embodiment, the switchedcurrent limit is calculated by determining the current capacity/limit ofthe electrical power input and then subtracting any measured orotherwise known currents associated with un-switched loads.

In some cases determining the switched current limit (304) also includesadjusting the switched current limit to account for variations in linevoltage received at the electrical power input. For example, duringoperation, changes in line voltage affect the available source current.To account for this type of variation, the switched current limit can beadjusted down (e.g., by 10-20%) to allow for increasing input currentsdue to input voltage drops caused by other loads on the sourcedistribution lines. Providing this type of hysteresis can in some caseshelp prevent or reduce the likelihood of false alarms due to constantpower switching among loads and re-checks of the currents when the loadis near the maximum of the switched current limit. In some cases theswitched current limit may also be set to account for variations in linevoltage in different areas of the world, such as the U.S. or Europe. Forexample, some embodiments of the invention compensate for world voltagesource ranges by automatically limiting the maximum current regardlessof the line voltage.

Returning to FIG. 3 , the method 300 also includes measuring the currentdrawn by each switched electrical load or device (306). For example,referring to FIG. 2 , the controller 208 is configured to measure thecurrent associated with each of the switched power outputs 204 using thecurrent sensor 210. After measuring the current drawn by each output,the measured currents can be saved in memory for future use.

With continued reference to FIG. 2 , in some cases the current drawn byeach output 204 is determined by switching on each output 204 one at atime, measuring the current drawn by the load coupled to the output,saving the measured current value, switching power off to thatparticular output, switching power to the next output, and starting thesequence over. This sequence allows for measuring the currentsassociated with the switched outputs 204 one at a time with the singlecurrent sensor 210. This method can also reduce the likelihood that toomuch power will be requested from the power input 202 duringinitialization of the power scheme, thus decreasing the risk of an earlyovercurrent fault.

In some cases a built-in delay is provided between switching power toeach power output 204 and measuring the current drawn by the output. Forexample, the controller 208 may be configured to activate one of theswitches 206 to apply power to a power output 204 and an associatedload, and then wait for some time (e.g., several milliseconds) beforemeasuring the current associated with that power output 204 and load.This procedure can help account for variations in how differentelectrical loads power up (e.g., to account for ramping currents, etc.)and ensure that accurate current measurements are made for each poweroutput 204.

Returning to FIG. 3 , after the currents of each switched device aremeasured (306), the currents associated with any un-switched loads aremeasured (302) and the switched current limit is determined (304), themethod 300 further includes grouping (308) the switched outputs andassociated electrical loads into one or more load groups based on theswitched current limit and the measured currents. The load groups arethus defined to include one or more of the switched outputs andcorresponding switched electrical loads. Taking into account thedetermined switched current limit associated with the electrical powerinput, each group preferably includes a number of switched outputs andloads, but the sum of the measured currents associated with the selectedoutputs/loads does not exceed the switched current limit. Accordingly,upon switching power to a particular load group, the combined currentdraw of the outputs/loads within the load group will not be greater thanthe previously determined switched current limit.

A number of methodologies can be used to group the switched outputs andswitched loads together and embodiments of the invention are notintended to be limited to only certain methods. According to someembodiments, the step 308 seeks to maximize the number of switchedoutputs and devices within a single load group so that as many possibleswitched outputs/loads will be powered at a time without exceeding thepreviously determined switched current limit. In certain embodimentsdifferent combinations of switched outputs/loads may be evaluated byadding the saved current measurements for a particular group of switchedoutputs/loads and comparing the result to the switched current limit. Ifthe combined current draw is greater than the switched current limit, asmaller group or subset of the switched outputs/loads may then beevaluated. This approach may proceed until the largest combination ofswitched outputs/loads with a combined current draw below the switchedcurrent limit is determined. After determining the makeup of a firstload group in this manner, the remaining switched outputs/loads can thenbe grouped into additional load groups in the same manner.

Following the grouping of the switched outputs and correspondingelectrical loads, the method 300 includes applying power to each of theload groups (310). In some embodiments this involves activating switchesto apply electrical power from the common power source to the loadgroups according to a power sequence. In certain cases the electricalpower may be applied to each load group for a determined period of timebefore removing power from the load group and applying power to the nextload group in the sequence. The sequence for applying power to the loadgroups can place the load groups in any desired order. In someembodiments the power sequence places the load groups in order from theload group with the greatest current draw not exceeding the switchedcurrent limit first to the load group with the lowest current draw last.

According to some embodiments, as power is removed from one load groupand applied to the next load group in the power sequence, short delay isinserted between removal and subsequent application to limit inrushcurrents from multiple electrical loads being connected to theelectrical power input at the same time. For example, in some cases thecontroller 208 of the system 200 shown in FIG. 2 may be configured todeactivate one group of switches 206, then delay approximately 100 ms,and then activate another group of switches 206 to apply power toanother load group.

After applying power to one of the load groups in step 310, the method300 determines whether all load groups have received power at step 314.If not, the method advances to the next load group in the power sequence(316) and switches power to the next load group. After all load groupshave been powered according to the power sequence, the method 300returns to the beginning of the process to re-measure the currents ofthe switched outputs and switched loads (306), re-measure the currentsof each un-switched device (assuming the presence of one or moreun-switched devices) and re-determine the switched current limit (304)to the extent necessary. Based on this updated information, the methodre-groups (308) the switched outputs/loads. During re-grouping, the sameprocedure of maximizing the number of switched outputs/loads in eachload group can be followed in certain instances. Using the sameprocedure during the second and subsequent iterations of this processcan be especially useful for charging batteries. For example, asprevious cycles increase the charge of the batteries, an increasingnumber of batteries (i.e., switched loads) can be included in the sameload group. Depending upon the extent of the re-grouping, the powersequence may be revised to activate switches for applying power to thedesired switched outputs/loads. The process of re-measuring currents andregrouping switched outputs/loads continues as needed until power is nolonger needed or a change in the process is necessary.

One type of event that can interrupt the method 300 described above is achange to the switched electrical loads and/or un-switched electricalloads that causes an increased current draw from the electrical powerinput above the switched current limit. According to some embodiments,the method 300 also includes monitoring (312) the switched andun-switched loads to determine if a current increase occurs. Althoughthe monitoring step 312 is illustrated at a particular point in method300, it is contemplated that in some embodiments the monitoring step 312may be ongoing throughout the method 300, simultaneous with the othersteps. Upon detecting (314) an increase in the current rising above theswitched current limit, the method 300 may interrupt the currentactivities to once again start the process at the beginning so that thecurrents can be re-measured and the switched electrical loads can bere-grouped as necessary to prevent an immediate overcurrent event. Inaddition, the switched current limit can be adjusted as necessary basedon the detected increase in current. For example, if a user abruptlyturns on a device connected to an un-switched power output causing anincrease in un-switched current flow, the switched current limit can beadjusted to reflect the decrease in available current for the switchedloads, thus giving priority to the un-switched load.

FIG. 4 is an illustration of an indicator panel 400 for a loadmanagement system in accordance with an embodiment of the invention. Insome cases the indicator panel provides an indication to a user of thecurrent state of the load management system, including scanning,powering, fault, etc. In some cases the load management system has thefollowing modes:

Scanning

Powering

Fault

Not powered up

Powered up

Sensing something attached to the auxiliary power receptacle

Not sensing something attached to the auxiliary power receptacle.

The following description is just one possible example of an indicationscheme. When the load management system measures currents for theattached loads/devices, the loads (1, 2, 3, 4 . . . ) that are beingscanned are indicated by illuminating the number 402 that represents theload and flashing the number at a fast rate (e.g., ¼ second on, ¼ secondoff). In some cases the loads are individually scanned so there willnever be more than one load number flashing at one time during the scan.Once scanning all switched loads is complete and the load groups thatcan be powered at one time are determined, those load groups will bepowered on and indicated to the user by illuminating all of theapplicable load numbers (1, 2, 3, 4 . . . ) with a slow flashing light(e.g., 1 second on, 1 second off). As discussed above, a load group caninclude any combination of switched loads, and thus any combination ofload indicators 402 may flash.

In some circumstances, when there is a fault condition (e.g.,overcurrent, high temperature, etc.), none of the load indicators 402will be illuminated. If the fault condition is a high temperature, thehigh-temperature icon 404 will be illuminated and flashing (e.g., ½second on, ½ second off). When the load management system is coupledwith an input power source, a power-on icon 406 can be illuminated. Whenthe system senses an attached load on its un-switched power output(e.g., an auxiliary power receptacle), the power plug icon 408 canilluminate. When there is nothing attached to the un-switched poweroutput, or a load is attached and the power is sufficiently low (e.g.,0.2 amps) or the load power is off, the power plug icon 408 will not beilluminated.

Embodiments of the invention, including aspects related to the loadmanagement system 200 and method 300 for applying power described abovecan be implemented in a wide variety of application-specificembodiments. Embodiments of the invention are not limited to anyparticular application, but may be directed to providing and managingpower for a wide variety of electrical loads, including, for example,electrical devices such as notebook and tablet computers, cell phones,smart phones, PDAs, cameras, music players, and/or GPS devices, amongothers. As one example, a load management system such as one describedherein could be provided within or in conjunction with a vehicle powersystem in order to power and/or charge a number of devices (e.g., GPS,cell phones, video players, music players, etc.) within the vehicle.

As mentioned above, in some cases an embodiment of the invention may beincorporated within a battery charging station, such as a desktopcharging station or a notebook charging cart. These particularapplications will now be discussed in more detail.

FIGS. 5A-5D are perspective views of a notebook battery charging station500 in accordance with an embodiment of the invention. As is known, mostnotebook/laptop computers have one or more removable batteries that canbe disconnected and uncoupled from the laptop for charging, maintenance,replacement, etc. In some embodiments of the invention, the chargingstation 500 includes a housing 502 configured to receive and/or hold oneor more laptop batteries 504. The charging station 500 also includes oneor more corresponding charging circuits 506 and cables 508 and/orconnectors 510 for coupling the one or more batteries 504 to thecharging circuits 506. The charging station 500 can be configured tohold as many laptop batteries as desired. In some embodiments, thestation holds at least 5 laptop batteries. In other embodiments, thestation is configured to hold more than 10 batteries, (e.g., up to 20,30, or 40 batteries).

Turning to FIG. 5D, the charging station 500 includes circuitry adaptedto charge the one or more batteries coupled to the station. A powersupply system can be provided for charging the plurality of batterieswhen received in the station. The power supply system is useful forrecharging the batteries of the laptops. The power supply systemincludes a device to receive power into the cart, such as a male powercord extending from the cart or a female receptacle in or on thecharging station. Embodiments of the power supply system include a powerbrick 520 that in some cases converts AC power to DC power which isultimately routed to each laptop battery stored within the station 500.In some embodiments an external AC/DC power converter provides DC powerthat is received at the charging station. In some cases the chargingcircuitry includes one or more indicators, such as LEDS 518, thatilluminate when the charging circuitry is currently in use.

In some embodiments the charging station 500 may be configured toreceive entire laptops, rather than only a laptop battery. In suchcases, a networking connection (e.g., Ethernet) can be provided forconnecting the laptop computers to a network when stored in the chargingstation. Such a connection is useful for providing software updates tothe laptops when they are not in use. Of course, the charging station500 can provide each laptop with other connections. Further, one or morepower outlets (not shown) can be provided on the exterior of thecharging station 500 if desired. Such power outlets allow foraccessories such as printers and projectors to be plugged into thecharging station so that additional power cords do not have to be runfrom the station to the wall.

In some cases simultaneously charging many notebooks or notebookbatteries can exceed the limited current capabilities of typical walloutlets found in homes, schools, and business, as set forth by theNational Electrical Code and foreign equivalents. In addition, the powerrequirements of the multiple notebooks/batteries 504 can exceed thecapacity of the DC power source 520 that provides the bulk chargecurrent for the battery charging electronics. According to someembodiments, the charging station 500 incorporates a load managementsystem, such as the system 200 illustrated in and described with respectto FIG. 2 . The load management system interfaces between the DC powersource 520 and the charging circuits 506 to manage the electrical powerreceived from the power source 520 and distribute it to the chargingcircuits and thereafter the batteries 504 in the manner described abovewithout exceeding the branch-circuit current capability as set forth inthe National Electrical Code or the capability of the local DC powersource. Referring briefly to FIG. 2 , for example, the power source 520of the charging station can interface with the load management system200 at the electrical power input 202, although a hardwired or otherconnection may be used. In a similar fashion, each of the chargingcircuits 506 can interface with each of the electrical power outputs 204though, e.g., a hardwired or other connection. In addition, theun-switched auxiliary power output 212 can be coupled to an exteriorpower outlet to the extent one is included with the charging station500.

FIGS. 6A-6D are views of a laptop charging/storage cart 600 inaccordance with an embodiment of the invention. FIGS. 7A-7B areperspective views of another laptop cart 700 in accordance with anotherembodiment of the invention. The carts can include any structure usefulfor holding a plurality of laptop computers or other mobile computingdevices and providing power and/or network connectivity to the laptopcomputers. Multiple examples of carts that can be useful for storingand/or charging laptop computers and other mobile computing devices aredisclosed in co-owned and copending U.S. patent application Ser. No.13/025,782, the entire content of which are hereby incorporated hereinby reference.

Returning to FIGS. 6A-7B, as shown, the carts 600, 700 can each includea cabinet 630 defining an interior space for storing a plurality oflaptop computers. The interior space may in some cases include a laptopdocking station 650 for each laptop disposed in the cart. As shown inFIGS. 6A-7B, in some embodiments the cabinets 630 include a doorassembly 670 having one or more doors to close the interior spacebounded by a top, bottom, and four sides. Such doors can be of any styleincluding, sliding, openable from the top, or swingable outwardly. Insome embodiments, the door may optionally be locked to secure the mobilecomputing devices within the cart. In some embodiments, wheels 610 canbe positioned on an underside of the cabinet 630 to facilitate easymovement of the carts. Further, handles 620 can be provided tofacilitate the movement of the cart.

As shown in FIGS. 6B-6C, a plurality of docking stations 650 can beconfigured to hold the laptop computers in a generally verticalposition, or as shown in FIG. 7A, the plurality of docking stations 650can be configured to hold the laptop computers in a generally horizontalorientation positioned on a shelf 654. The carts can be configured tohold as many laptops as desired. In some embodiments, the carts hold atleast 10 laptop computers in their interior spaces. In otherembodiments, the carts are configured to hold between 10 and 40 (e.g.,20 and 30) laptops in their interior spaces.

Further, as shown in FIGS. 7B-7D, one or more auxiliary power outlets730 can be provided on the exterior of any cart. Such power outletsallow for accessories such as printers and projectors to be plugged intothe cart so that additional power cords do not have to be run from thecart to the wall. FIGS. 7C-7D are front perspective views of auxiliarypower outlets 730 having a cover 790 (in the open position) to reducethe likelihood that foreign objects will be placed in the auxiliarypower outlet 730. In FIG. 7C, the cover is open to provide access to aUnited States style power outlet, while in FIG. 7D the cover is open toprovide access to a European style power outlet.

An network connection (e.g., Ethernet) system (not shown) can beprovided for connecting the plurality of laptop computers to a networkwhen stored within the interior space. The network connection systemincludes at least one device for a cart to communicate with the network.In some embodiments, this device includes a wire extending from thecart. In other embodiments, the cart includes a wireless transmitterthat allows the cart to communicate with the network. Ultimately, thecart allows for communication between each laptop stored in the cart andthe network. Such a connection is useful for providing software updatesto the laptops when they are not in use. In general, these systems areinternal to a cart and are not easily accessible to users. Of course,the carts 600, 700 can provide each laptop with other connections.

In some embodiments, a cart includes an air circulation system to coolthe plurality of laptop computers when they are in the interior space.The air circulation system can include at least one fan 770 disposed inan outer surface of the cabinet 630 to facilitate air exchange betweenthe interior and the exterior of the cabinet. In some embodiments, oneor more passive vents are provided in the exterior of the cabinet tofacilitate air circulation.

A power supply system can be provided for charging the plurality oflaptop computers when stored within the interior spaces of the carts600, 700. Each power supply system includes a device to receive powerinto the cart, such as a male power cord extending from the cart or afemale receptacle in or on the cart. Embodiments of the power supplysystem convert AC power to DC power and ultimately route the power toeach laptop stored within the carts 600, 700. The power supply systemmay also route power to other subsystems within the carts 600, 700,including the auxiliary outlets, networking circuitry, and/or aircirculation system described above.

As noted above with respect to the charging station 500 illustrated inFIGS. 5A-5D, in some cases simultaneously charging many notebooks ornotebook batteries can exceed the limited current capabilities oftypical wall outlets found in homes, schools, and business, as set forthby the National Electrical Code and foreign equivalents. In addition,the power requirements of the multiple notebooks/batteries 504 canexceed the capacity of the DC power source 520 that provides the bulkcharge current for the battery charging electronics. These samelimitations can also affect the performance of laptop charging/storagecarts, such as the carts 600, 700 described herein.

According to some embodiments, the power supply system of a laptop cartincorporates a load management system, such as the system 200illustrated in and described with respect to FIG. 2 . In certainembodiments, the load management system interfaces between the AC inputbox of the power supply system and the various subsystems within thecart powered by the power supply system. The load management systemmanages the electrical power received from the AC input and distributesit to the docking stations 650 within each cart 600, 700, as well as tothe auxiliary outlets, networking circuitry, and/or air circulationsystem described above. As described above (e.g., with respect to FIGS.2-3 ), the load management system is configured to distribute electricalpower to these systems within the carts 600, 700 without exceeding thebranch-circuit current capability as set forth in the NationalElectrical Code.

FIG. 8 is a high-level schematic of a power supply system 800 for anotebook charging cart in accordance with an embodiment of theinvention. As just one example, the power supply system 800 can beincorporated within either of the carts 600, 700 discussed above. Thepower supply system 800 includes an AC input box 850 that is configuredto receive power into the cart, and may include a female receptacle inor on the cart or a male power cord extending from the cart. The ACinput box 850 is coupled to a load management system 801, also referredto in this example as a power control box. The load management system801 manages the power received from the AC input box and distributes itto a number of subsystems within the power supply system. According toan embodiment of the invention, the load management system 801 providesfunctionality similar to the system 200 described with respect to FIG. 2.

For example, the load management system 801 includes an electrical powerinput receptacle 802 that couples with the AC input box and receiveselectrical power from the AC input box. The system 801 also includes anumber of switched power output receptacles 804, which are coupled to anumber of power extension strips 852. Each extension strip 852 includesmultiple female power receptacles for plugging in up to five laptopcomputers (in this embodiment a sixth receptacle is not used), thusproviding power for up to thirty laptop computers within the cart. Theload management system 801 also includes a networking power output 814which is coupled to a networking power box 854, and an auxiliary output812 which is coupled to an auxiliary outlet 856. The load managementsystem 801 receives operating power from an AC/DC converter 858 througha power input 822. In addition, in this embodiment the load managementsystem 801 also includes three power outputs 860 coupled to a number offans 862 which make up part of an air circulation system of the cart.Further, the load management system 801 includes a power output 864 forpowering a temperature sense board 866, and power outputs 868 forpowering an LED indication board 870.

As discussed above with respect to FIG. 2 , the load management system801 in FIG. 8 includes a controller that is configured to distribute theavailable electrical power from the power input 802 to the switchedpower outputs 804 by grouping the power outputs 804 and then selectivelyapplying the electrical power to the groups of power outputs (and byextension, the power extension strips 852 and laptops coupled thereto)according to a power sequence. As with the system 200, the loadmanagement system 801 also provides un-switched (e.g., continuous)electrical power to one or more power outputs, including in this casethe auxiliary power output 812 and the networking power output 814, aswell as the power outputs 860, 864, and 868 for the air circulationsystem fans 862, the temperature sense board 866, and the LED indicationboard 870, respectively. Of course any number of additional poweroutputs can be included in the load management system 801, and anycombination of the outputs can be switched or un-switched dependingupon, for example, the importance of the functions provided and thedesirability of providing those functions uninterrupted, e.g.,un-switched.

As discussed with respect to the system 200, the system 801 alsoincludes a number of current sensors (not shown) coupled to the switchedpower outputs 804 and the un-switched power outputs to help determinethe currents drawn by the various subsystems coupled to the loadmanagement system 801. The controller (not shown) can then use thosecurrents, along with a current limit of the power source to group theswitched outputs and apply power to each of the switched outputsaccording to a determined power sequence as discussed above with respectto the system 200. Accordingly, the load management system 801 allowsthe power supply system 800 to prioritize electrical power distributionfor un-switched loads, while providing the remaining available power tothe laptop computers through the switched power outputs 204 in anefficient, sequenced charging scheme.

According to certain embodiments of the invention, a load managementsystem is configured to monitor the currents of the notebook computersor individual batteries and group them in an efficient way to charge themost notebooks/batteries at the same time without exceeding the branchcircuit current limits or bulk power source limits. After a specifiedperiod of time, the system switches power from a first grouping ofnotebooks or batteries to a second grouping of notebooks/batteries andprovides power to the second group for a specified period of time. Asmany groups as desired can be provided, depending on the number ofnotebooks the cart is adapted to hold. This monitoring of current andgrouping continues until all notebooks or batteries are removed from thecart/charging station or the charging is completed. If additionalnotebooks or batteries are added to the cart/charging station, thecurrents may be measured again and notebooks and batteries can bere-grouped if necessary for optimal charging. According to someembodiments, a system that couples to full laptop computers, mayautomatically switch the Ethernet connections on by applying power tothem after the charging is completed the system so the notebooks can bemanaged after they have sufficient charge.

According to certain embodiments, a load management system also monitorsto see if an external device is plugged into any provided auxiliarypower receptacles. If the system detects such an external device it cangive the device top priority and automatically remove or reduce power tothe notebooks, batteries, networking circuitry, and other lower prioritysubsystems. If the system detects the external device has been removed,it can begin applying power to the other subsystems. Accordingly, insome embodiments a system automatically and selectively directs power toan external device, notebook/battery charging systems, and notebookmanagement systems, in that order of priority. Further, in someembodiments, the system monitors the temperature of the cart or chargingstation and if it detects an over-temperature situation, it removespower to all notebooks and/or batteries. In some embodiments, thecontroller automatically re-applies power when the over temperaturesituation has been corrected. In some embodiments there is at least a 30mS delay before an over temperature detection to prevent a falseindication during electromagnetic interference events. An indication tothe user of an over temperature situation can be provided by a blinkingLED on an LED indication board.

FIGS. 9A-9C are a flow diagram 900 illustrating steps and decisionpoints for charging multiple notebook computers in accordance with anembodiment of the invention. The flow diagram 900 generally illustratesa methodology for charging thirty notebook computers in a setting with a100/110/120 Volt, 15 Ampere (“Amp”) input power source, and correspondsto the embodiment of the power supply system 800 described with respectto FIG. 8 . The charging methodology begins with an initialization setup902. The initialization setup 902 begins upon an initial powering on ofthe power supply system and load management system. First steps in theinitialization setup 902 include turning on a Power On LED, a logo LED,and the auxiliary power output.

The initialization sequence then completes an initial test of the loadmanagement system 801 to determine if any overcurrents exist prior toinitiating the charging sequence. During the test, each switched poweroutput 804 is turned on for one second, along with a correspondingcoupled power extension strip 852 and any coupled notebook computers.FIGS. 9A-9C refer to a switched power output and extension strip as a“bank”. A charge timer is then set to ten minutes and the current ofeach bank (i.e., switched power output 804 and extension strip 852) isscanned for thirty seconds each. Following is a five-second current scanof the networking power output 814. Following the scans, the measuredcurrents are saved to memory.

The charging methodology of FIGS. 9A-9C includes a first query 904 ofthe currents measured during the initial scan in the setup 902 todetermine if an initial overcurrent is present. The first query 904checks if the currents measured during the one second scan or the thirtysecond scan in addition to current detected on the auxiliary poweroutput (“AUX”) and the networking power output (“SW”) are greater thantwelve Amps. The query uses twelve Amps as the comparison point becausethe National Electrical Code (NEC) sets the limits for 15-amp sitebranch wiring to 12-amps. (The foreign equivalent for 10-amp branchcircuits is 8-amps.) Accordingly, devices plugging into wall receptaclescannot exceed 12 Amps in North America. If the measured currents aregreater than 12 Amps, the load management system enters an endless loop906 in which the LEDS are flashed at a rapid rate to indicate theovercurrent event.

If the measured currents are less than or equal to 12 Amps, a secondquery 908 is made to determine if the system's temperature is within adesired range. If not, the system turns off the switched power outputs(i.e., Banks 1-6) and flashes the High Temp LED. If the system is withintemperature range, then the auxiliary current is compared to 0.2 Amps inquery 910 to make a determination as to whether or not an externaldevice coupled to the auxiliary power output is turned on and the systemilluminates the AUX LED at 912.

Following these initial evaluations, the charging methodology beginscomparing the currents measured on each switched power output in orderto group the power outputs into one or more load groups and then applypower to the load groups. The methodology follows an iterative approachin which different combinations of switched power outputs are comparedto a switched current limit to determine the groupings. In this case,the switched current limit is equal to ten Amperes less the currents onthe auxiliary and networking outputs (10 A-AUX-SW). Ten Amperes is usedinstead of the actual NEC limit of twelve amperes in order to add inhysteresis around the threshold to avoid constant switching when levelsnear the threshold.

The comparisons begin with query 920, in which it is determined whethera combination of all six switched power outputs (all six “banks”) has acombined current less than the switched current limit. If they do, onlyone load group is formed including all the banks and this is powered onfor a ten minute period at 922. After the ten minute period expires, theprocess starts over again. If at any time during the current comparisonsthe total current is greater than twelve amps (query 924), the processis immediately interrupted to re-measure the various currents (step 926)and start the grouping process over.

If the current on all six banks is not less than the switched currentlimit at query 920, then the comparison continues at query 930 in whichit is determined if the first five banks have a combined current lessthan the switched current limit. If so, a first load group including thefirst five banks is powered for ten minutes at 932, and then a secondload group including only bank six is powered for ten minutes.

As can be seen in FIGS. 9A-9C, according to this embodiment, a largenumber of load groupings (defined in rectangular boxes 940) are possibleaccording to the illustrated charging methodology depending upon thecurrents measured on each individual switched power output, as well asthe currents measured on the AUX and SW outputs. In addition, in thisembodiment the query 924 is continuously made throughout the variouscurrent comparisons and if at any time the combined total current isgreater than twelve Amps, then the sequence is interrupted and thecurrents are re-measured in order to re-group the power outputs intoload groups whose current does not exceed the switched current limit.FIGS. 10A-10B, 11A-11C, and 12A-12B illustrate additional chargingmethodologies similar in many respects to the methodology illustrated inFIGS. 9A-9C. The methodology of FIGS. 10A-10B corresponds to a computercart with twenty laptop computers being powered with a 100/110/120 Volt,15 Amp input power source. FIGS. 11A-11C, and 12A-12B correspond tocomputer carts powered by a 220/230/240 Volt input source. FIGS. 11A-11Cillustrate a thirty-notebook methodology, while FIGS. 12A-12B illustratea twenty-notebook methodology.

Additional Notes

Example 1 includes subject matter (such as a method, means forperforming acts, machine readable medium including instructions thatwhen performed by a machine cause the machine to performs acts, or anapparatus configured to perform) for distributing electrical power to aplurality of electrical loads comprising: coupling an existing group ofelectrical loads to a common power source through a load managementsystem; measuring an aggregate group current drawn by at least theexisting group of electrical loads and comparing the measured aggregategroup current to an aggregate group current threshold value; when themeasured aggregate group current exceeds the aggregate group currentthreshold value: increasing a number of subgroups of the existing group,using subgroups that are formed without requiring information aboutindividual current associated with the individual electrical loads;sequentially applying power to individual subgroups duringnon-overlapping time periods; sequentially measuring at least acorresponding current drawn by the individual subgroups while power isapplied to the subgroups; and sequentially comparing the measuredcurrent to a threshold value, and when the measured current exceeds thethreshold value, repeating the increasing the number of subgroups, thesequentially applying power, the sequentially measuring at least thecorresponding current, and the sequentially comparing at least themeasured current to a threshold value; and when the measured currentdoes not exceed the threshold value, repeating the sequentially applyingpower, the sequentially measuring at least the corresponding current,and the sequentially comparing the measured current to a thresholdvalue.

In Example 2, the subject matter of Example 1 may optionally include,where the increasing the number of subgroups comprises dividing theexisting group into two subgroups.

In Example 3, the subject matter of any one or both of Examples 1 and 2may optionally include, wherein the increasing the number of subgroupscomprises incrementing the number of subgroups by one.

In Example 4, the subject matter of any one or more of Examples 1-3 mayoptionally include comprising distributing the plurality of electricalloads across the increased number of subgroups.

In Example 5, the subject matter of any one or more of Examples 1˜4 mayoptionally include wherein when the measured current exceeds thethreshold value, repeating the increasing the number of subgroups, thesequentially applying power, the sequentially measuring at least thecorresponding current, and the sequentially comparing the measuredcurrent to a threshold value, wherein the repeating is performed until asubgroup criterion is met.

In Example 6, the subject matter of Example 5 may optionally includewherein the subgroup criterion includes the following condition themeasured current corresponding to each of subgroups being below thecorresponding threshold value associated with the subgroup.

In Example 7, the subject matter of any one or more of Examples 5-6 mayoptionally include wherein the subgroup criterion includes the followingcondition: the subgroups have been increased to a maximum availablenumber of subgroups and the aggregate group current exceeds theaggregate group current threshold value.

In Example 8, the subject matter of any one or more of Examples 1-7 mayoptionally include wherein sequentially measuring at least acorresponding current drawn by the individual subgroups while power isapplied to the subgroups, includes including in the measured current, inaddition to the current drawn by the individual subgroup, at least oneof (1) an auxiliary power output current and (2) a switched power outputcurrent.

In Example 9, the subject matter of any one or more of Examples 1-8 mayoptionally include wherein increasing the number of subgroups furtherincludes correspondingly decreasing the non-overlapping time periodassociated with subgroups for the sequentially applying power to theindividual subgroups.

Example 10 includes or uses subject matter (e.g., a system, apparatus,article, or the like) for distributing electrical power to a pluralityof electrical loads comprising: a load management system, coupling anexisting group of electrical loads to a common power source; a currentmeasurement circuit to measure an aggregate group current drawn by atleast the existing group of electrical loads; a comparator circuit,coupled to the current measurement circuit, comparing the measuredaggregate group current to an aggregate group current threshold value; acontroller circuit, coupled to the comparator circuit, configured for,when the measured aggregate group current exceeds the aggregate groupcurrent threshold value: increasing a number of subgroups of theexisting group, using subgroups that are formed without requiringinformation about individual current associated with the individualelectrical loads; sequentially applying power to individual subgroupsduring non-overlapping time periods, using the load management system;sequentially measuring, using the comparator circuit, at least acorresponding current drawn by the individual subgroups while power isapplied to the subgroups; and sequentially comparing, using thecomparator circuit, the measured current to a threshold value, and whenthe measured current exceeds the threshold value, repeating theincreasing the number of subgroups, the sequentially applying power, thesequentially measuring at least the corresponding current, and thesequentially comparing at least the measured current to a thresholdvalue; and when the measured current does not exceed the thresholdvalue, repeating the sequentially applying power, the sequentiallymeasuring at least the corresponding current, and the sequentiallycomparing the measured current to a threshold value.

In Example 11, the subject matter of Example 10 may optionally include,wherein the controller circuit is configured for increasing the numberof subgroups including dividing the existing group into two subgroups.

In Example 12, the subject matter of any one or both of Examples 10 and11 may optionally include, wherein the controller circuit is configuredfor increasing the number of subgroups including incrementing the numberof subgroups by one, and distributing the plurality of electrical loadsacross the increased number of subgroups.

In Example 13, the subject matter of any one or more of Examples 10-12may optionally include, wherein the controller circuit is configuredfor, when the measured current exceeds the threshold value, repeatingthe increasing the number of subgroups, the sequentially applying power,the sequentially measuring at least the corresponding current, and thesequentially comparing the measured current to a threshold value,wherein the repeating is performed until a subgroup criterion is met.

In Example 14, the subject matter of Example 13 may optionally include,wherein the subgroup criterion includes the following condition: themeasured current corresponding to each of subgroups being below thecorresponding threshold value associated with the subgroup.

In Example 15, the subject matter of any one of Examples 13 or 14 mayoptionally include, wherein the subgroup criterion includes thefollowing condition: the subgroups have been increased to a maximumavailable number of subgroups and the aggregate group current exceedsthe aggregate group current threshold value.

Example 16 includes subject matter for distributing electrical power toa plurality of electrical loads (such as a method, means for performingacts, machine readable medium including instructions that when performedby a machine cause the machine to performs acts, or an apparatusconfigured to perform) comprising: applying power to a plurality ofelectrical loads coupled to a common power source through a loadmanagement system; measuring a current drawn by the plurality ofelectrical loads and comparing the measured current to a thresholdvalue; if the measured current exceeds the threshold value: grouping theplurality of electrical loads into at least a first load group and asecond load group; applying power to the first load group; measuring acurrent drawn by the first load group and comparing the measured currentof the first load group to the threshold value; and if the measuredcurrent of the first load group does not exceed the threshold value:applying power to the second load group; measuring a current drawn bythe second load group and comparing the measured current of the secondload group to the threshold value.

Each of these non-limiting examples can stand on its own, or can becombined in various permutations or combinations with one or more of theother examples.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description.

The Abstract is provided to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A method for distributing electrical power to a plurality ofelectrical loads, the method comprising: coupling an existing group ofthe electrical loads to a common power source through a load managementsystem, wherein the plurality of electrical loads are coupled to a powersystem of a vehicle; comparing an aggregate group load characteristicassociated with at least the existing group of the electrical loads toan aggregate group load characteristic threshold value; and determiningthat the aggregate group load characteristic exceeds the aggregate groupload characteristic threshold value and, in response: increasing anumber of subgroups of the existing group, using subgroups that areformed without requiring information about individual loadcharacteristics associated with individual electrical loads; andapplying power to individual subgroups during non-overlapping timeperiods.
 2. The method of claim 1, further comprising: in response todetermining that the aggregate group load characteristic exceeds theaggregate group load characteristic threshold value: comparing a loadcharacteristic associated with the individual subgroups while power isapplied to the subgroups to a threshold value, and when the loadcharacteristic exceeds the threshold value, repeating the increasing thenumber of subgroups, the applying power, and the comparing at least theload characteristic to a threshold value; and when the loadcharacteristic does not exceed the threshold value, repeating theapplying power, and the comparing the load characteristic to a thresholdvalue.
 3. The method of claim 2, wherein when the load characteristicexceeds the threshold value, repeating the increasing the number ofsubgroups, the applying power, and the comparing the load characteristicto a threshold value, wherein the repeating is performed until asubgroup criterion is met.
 4. The method of claim 3, wherein thesubgroup criterion includes the following condition: the loadcharacteristic corresponding to each of subgroups being below thecorresponding threshold value associated with the subgroup.
 5. Themethod of claim 3, wherein the subgroup criterion includes the followingcondition: the subgroups have been increased to a maximum availablenumber of subgroups and the aggregate group load characteristic exceedsthe aggregate group load characteristic threshold value.
 6. The methodof claim 1, where increasing the number of subgroups comprises dividingthe existing group into two subgroups.
 7. The method of claim 1, whereinincreasing the number of subgroups comprises incrementing the number ofsubgroups by one.
 8. The method of claim 1, further comprising:distributing the plurality of electrical loads across the increasednumber of subgroups.
 9. The method of claim 1, wherein increasing thenumber of subgroups further includes correspondingly decreasing thenon-overlapping time period associated with subgroups for the applyingpower to the individual subgroups.
 10. The method of claim 1, whereinthe aggregate group load characteristic is a current.
 11. The method ofclaim 1, wherein coupling the existing group of the electrical loads tothe common power source through the load management system, wherein theplurality of electrical loads are coupled to the power system of thevehicle includes: coupling the existing group of the electrical loads tothe common power source through the load management system, wherein theplurality of electrical loads are coupled to the power system of anautomobile.
 12. The method of claim 1, wherein coupling the existinggroup of the electrical loads to the common power source through theload management system, wherein the plurality of electrical loads arecoupled to the power system of the vehicle includes: coupling theexisting group of the electrical loads to the common power sourcethrough the load management system, wherein the plurality of electricalloads are coupled to the power system of an aircraft.
 13. An apparatusfor distributing electrical power to a plurality of electrical loadscoupled to a power system of a vehicle, the apparatus comprising: a loadmanagement system to couple an existing group of electrical loads of thevehicle to a common power source; a comparator circuit to compare anaggregate group load characteristic associated with at least theexisting group of the electrical loads to an aggregate group loadcharacteristic threshold value; and a controller circuit coupled to thecomparator circuit and configured for determining that the aggregategroup load characteristic exceeds the aggregate group loadcharacteristic threshold value and, in response: increasing a number ofsubgroups of the existing group, using subgroups that are formed withoutrequiring information about individual load characteristics associatedwith the individual electrical loads; and applying, using the loadmanagement system, power to individual subgroups during non-overlappingtime periods.
 14. The apparatus of claim 13, wherein the controllercircuit is further configured for: in response to determining that theaggregate group load characteristic exceeds the aggregate group loadcharacteristic threshold value: comparing the load characteristicassociated with the individual subgroups while power is applied to thesubgroups to a threshold value, and when the load characteristic exceedsthe threshold value, repeating the increasing the number of subgroups,the applying power, and the comparing at least the load characteristicto a threshold value; and when the load characteristic does not exceedthe threshold value, repeating the applying power, and the comparing theload characteristic to a threshold value.
 15. The apparatus of claim 14,wherein the controller circuit is configured for, when the loadcharacteristic exceeds the threshold value, repeating the increasing thenumber of subgroups, the applying power, and the comparing the loadcharacteristic to a threshold value, wherein the repeating is performeduntil a subgroup criterion is met.
 16. The apparatus of claim 15,wherein the subgroup criterion includes the following condition: theload characteristic corresponding to each of subgroups being below thecorresponding threshold value associated with the subgroup.
 17. Theapparatus of claim 16, wherein the subgroup criterion includes thefollowing condition: the subgroups have been increased to a maximumavailable number of subgroups and the aggregate group loadcharacteristic exceeds the aggregate group load characteristic thresholdvalue.
 18. The apparatus of claim 13, wherein the controller circuit isconfigured for increasing the number of subgroups including dividing theexisting group into two subgroups.
 19. The apparatus of claim 13,wherein the controller circuit is configured for increasing the numberof subgroups including incrementing the number of subgroups by one anddistributing the plurality of electrical loads across the increasednumber of subgroups.
 20. The apparatus of claim 13, wherein the vehicleincludes an automobile.
 21. The apparatus of claim 13, wherein thevehicle includes an aircraft.
 22. The apparatus of claim 13, wherein theplurality of electrical loads coupled to the power system of the vehicleincludes a cellular phone.
 23. The apparatus of claim 13, wherein theplurality of electrical loads coupled to the power system of the vehicleincludes a global positioning system (GPS) device.
 24. The apparatus ofclaim 13, wherein the aggregate group load characteristic is a current.